Author Topic: Refurbishment of Used Stages/Vehicles  (Read 175188 times)

Online sanman

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Re: Refurbishment of Used Stages/Vehicles
« Reply #200 on: 02/03/2016 11:51 PM »
Looks like SpaceX is indeed making some design changes based on lessons learned from the landing:


http://www.theverge.com/2016/2/3/10906966/spacex-falcon-9-rocket-changes-reduce-refurbishment

Online Robotbeat

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Re: Refurbishment of Used Stages/Vehicles
« Reply #201 on: 02/04/2016 12:47 AM »
Here's a link to Shotwell's talk:
She's on at 2:43:00
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Online QuantumG

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Re: Refurbishment of Used Stages/Vehicles
« Reply #202 on: 02/04/2016 01:19 AM »
2:55:01 "We hope to fly a recovered Dragon later this year."
Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Offline Kaputnik

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Re: Refurbishment of Used Stages/Vehicles
« Reply #203 on: 02/05/2016 12:30 PM »
About those 'thrust fluctuations':
Seems that debris blown back up at an engine, maybe during touchdown, is a suspect.

Would it be possible to e.g. cold vent some LOX through the eight non-firing engines to help stop any debris being blown back into them? Are the engines even capable of doing this, and would it create a bit of a fireball?
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Offline JamesH

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Re: Refurbishment of Used Stages/Vehicles
« Reply #204 on: 02/05/2016 12:56 PM »
About those 'thrust fluctuations':
Seems that debris blown back up at an engine, maybe during touchdown, is a suspect.

Would it be possible to e.g. cold vent some LOX through the eight non-firing engines to help stop any debris being blown back into them? Are the engines even capable of doing this, and would it create a bit of a fireball?

My reading of GS comments is that they discovered something awry with the returned stage, and that has delayed the current launch. Now ingested FOD on landing would not do that, because that doesn't affect launch, so I suspect something else has been discovered, that was caused during the returned stage's launch. Supposition of course, but fits what we know. All good of course, every time they discover something, makes the next flight more reliable.
« Last Edit: 02/05/2016 01:58 PM by JamesH »

Online Robotbeat

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Re: Refurbishment of Used Stages/Vehicles
« Reply #205 on: 02/05/2016 01:31 PM »
About those 'thrust fluctuations':
Seems that debris blown back up at an engine, maybe during touchdown, is a suspect.
...
I sincerely doubt that. The throat is very small compared to the nozzle and it's dead air with nowhere to go.
« Last Edit: 02/05/2016 02:28 PM by Robotbeat »
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Offline hrissan

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Re: Refurbishment of Used Stages/Vehicles
« Reply #206 on: 02/06/2016 09:00 AM »
About those 'thrust fluctuations':
Seems that debris blown back up at an engine, maybe during touchdown, is a suspect.

Would it be possible to e.g. cold vent some LOX through the eight non-firing engines to help stop any debris being blown back into them? Are the engines even capable of doing this, and would it create a bit of a fireball?

My reading of GS comments is that they discovered something awry with the returned stage, and that has delayed the current launch. Now ingested FOD on landing would not do that, because that doesn't affect launch, so I suspect something else has been discovered, that was caused during the returned stage's launch. Supposition of course, but fits what we know. All good of course, every time they discover something, makes the next flight more reliable.
I will repeat my post from another thread, as it is more relevant here.

The returning stage experiences ~10g during the entrance burn... This should be ok for loads on tank walls and thrust structure (no 100-ton 2nd stage above), but some small piece of hardware like a GoPro camera or sensor mount might break lose from inside of the tank @10g plus hectic vibrations - hence foreign object ingestion in later tests.

If some structural components which have enough theoretical margin to sustain entrance burn environment happen to be damaged, this might lead to very deep thoughts on why the analysis was wrong, cause delays and even lead to redesign of some components.

Offline mme

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Re: Refurbishment of Used Stages/Vehicles
« Reply #207 on: 03/09/2016 09:53 PM »
What are the speculations or educated guesses on what will be required for refurbishment of stages/vehicles that have been recovered after flight, in order to make them flight-worthy again? (Was thinking mainly of the F9R booster, but Dragon would be relevant too)
...

SpaceX's goal is no refurbishment which Shotwell reiterated today:

https://twitter.com/pbdes/status/707682167112011776
Quote
SpaceX's Shotwell: the Falcon 9 first stage we recovered was in remarkable shape. Goal is no refurbishment.#satellite2016
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Offline guckyfan

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Re: Refurbishment of Used Stages/Vehicles
« Reply #208 on: 03/10/2016 07:12 AM »
SpaceX's goal is no refurbishment which Shotwell reiterated today:


Sounds reasonable to me. Given that no refurbishment means there is only some maintenance like cleaning, checking, replacing consumables.

Online oldAtlas_Eguy

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Re: Refurbishment of Used Stages/Vehicles
« Reply #209 on: 03/10/2016 04:45 PM »
The missing items in the statements is the price of the first flight if reused stages become more common. Would that first flight remain at $62M? Such that all costs are recovered for each flight and not amortized accros multiple flights.

First flight ~$60M
Reused vehicle flight ~$40M

The nifo seems to point to a cost of manufacture of a first stage at ~$20M
($20M/(1+20%[profit margin]))+$3M[refurbishment costs] = ~$20M

The assumption is the profit margin. Lower profit margins means higher manufacturing costs, higher profit marging lower manufacturing costs.

This no amortizing the manufacturing costs would work initially when the recover of stages is not low risk. Meaning the loss of a stage during recovery would not be a loss financially for SpaceX. Also initially ther will be more recovered stages that customers that will fly on them.

The NASA CRS and CC contracts may well assume a new booster and have been priced accordingly. So if 5 CRS/CC flights per year with a new booster and 3 additional flights on average on the recovered stages gives 20 launches in 1 year in the 2018-2020 timeframe. All the commercial and even some of the military is likely to all use recovered stages by then leaving NASA with its contracts already signed and negotiated flying the new boosters. Other NASA flights that are purchased in 2017 or later for 2019-2020 or latter flight may well use the reused booster price.

Eventually though SpaceX will have to change its pricing for the first flight in order to get someone to fly a new booster :).

Online Robotbeat

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Re: Refurbishment of Used Stages/Vehicles
« Reply #210 on: 03/10/2016 05:37 PM »
It's the other way around. The first flight would have to be offered a discount because it is unproven. The last flight would be full price because he could carry a full expendable payload. It doesn't make sense to charge the first customer the full amortization costs.  Can you imagine Delta Airlines charging it's first customers on a new jet tens of thousands of dollars per person ?
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Offline RanulfC

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Re: Refurbishment of Used Stages/Vehicles
« Reply #211 on: 03/10/2016 08:05 PM »
Aircraft, (actually any transportation system OTHER than launch vehicles really) amortization is figured over the lifetime of the vehicle which the user (example Delta Airlines) in fact DOES charge each and every passenger a portion thereof. The main metric is an assessed "lifetime" which is figured using a standard formula extrapolated from known data on and of similar vehicles.

In other words, it is dependent on data that no one (not even SpaceX) currently has enough of to make even a SWAG about. SpaceX can't make that determination unless and until they have flown enough stages to have a significant body of data to determine not only the overall lifetime of the airframe but its major components as well.

Simply, don't expect the pricing scheme to change all that much for a while. Overall SpaceX can reduce the price of any launch by a set amount to take into account stage reuse, (say for example from $60 million to $40 million) and apply it across the board for "X" number of flights, (the number 10 has been bandied about so use that) as a factor of overall launch costs. This allows them to further undercut the competition on pricing while maintaining enough overall profit per launch to allow for the occasional failure no matter where in the overall scheme it falls.

In actuality, the stage will progressively go from "reliable" (flight 1, technically flight 2) to "high probability of failure" (flight 10) which will cause some adjustment of the pricing. For example; $50 million per flight for the first 5 flights, $45 million for flights 6 through 8, $40 million for flight 9, and $30 million for flight 10. As experience and flight data builds up the airframe and major component lifetimes will become clearer and probably longer which will feed into the costing formula.

I should note though it's about as likely that they will find that a lifetime of 10 launches is too many and structural or major systems failure sets in around flight 5 (for an example) and prices will have to adjust accordingly there as well. Everything could look great right up until the tanks suddenly crumple at Max-Q on flight number 5 on multiple reused stages. This is still unknown territory.
(Note: I don't expect this to happen but no one has been here before so the actual situation is unknowable until it happens)

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Offline Jcc

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Re: Refurbishment of Used Stages/Vehicles
« Reply #212 on: 04/10/2016 09:48 PM »
Now that there is a recovered stage heading back to port that is intended to be re-flown, time to think more about refurbishment. Musk says that "test firing" 10 times will be sufficient to qualify it for relight.

I tend to think it will not just be ten 3 second static firings; perhaps a series of firings at different lengths and thrust levels? Are there sufficient sensors on the stage to provide all the diagnostic information needed? Will they also borescope the engines? Laser scan the tanks to look for slight deformations?

What else is appropriate to do?

ps. I think he said they will wash it also.
« Last Edit: 04/10/2016 10:10 PM by Jcc »

Offline Zed_Noir

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Re: Refurbishment of Used Stages/Vehicles
« Reply #213 on: 04/11/2016 04:58 AM »
...
I tend to think it will not just be ten 3 second static firings; perhaps a series of firings at different lengths and thrust levels? Are there sufficient sensors on the stage to provide all the diagnostic information needed? Will they also borescope the engines? Laser scan the tanks to look for slight deformations?
...
Keep in mind that the Merlins have a finite total burn time and finite number of engine startups.

Doing borescoping and laser scans are time consuming. So doing such tasks for returned cores is unlikely IMO without some indication of problems from the telemetry.

Online Coastal Ron

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Re: Refurbishment of Used Stages/Vehicles
« Reply #214 on: 04/11/2016 05:43 AM »
Keep in mind that the Merlins have a finite total burn time and finite number of engine startups.

Right, which they think they know, but they haven't had a chance to validate in an operational mode.  And even the ground testing is not fully operational, since it's not flying through the air, so I think what they plan to do is validate by similarity to some degree - hence the 10 test firings.

And the engines are replaceable and refurbishable, so let's remember that they have not yet announced they have achieved airline-like reusability.  It will be OK for them to replace and fix parts if needed, since even airliners fix and replace parts occasionally while they are operational.

Quote
Doing borescoping and laser scans are time consuming. So doing such tasks for returned cores is unlikely IMO without some indication of problems from the telemetry.

We know they have some sensors on each engine.  Maybe they have others too.  I think they have enough confidence that they will rely on what's already built in to the Falcon 9.

Plus we have to remember that they have a lot of experience running engines at their development and test facility, so I'm thinking that what they will be focused on is changes that may have been caused by the re-entry and landing part of the flight profile, not the ascent.  And those changes might not be limited to the engine, but the structures and misc. protection systems they have.
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Offline AC in NC

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Re: Refurbishment of Used Stages/Vehicles
« Reply #215 on: 04/16/2016 07:46 PM »
What else is appropriate to do?

ps. I think he said they will wash it also.

Would be hilarious to get a High School to setup on the east side of intersection at Grouper and Snapper and have girls in bikinis trying to get the attention of the KAMAG driver for a fundraiser.

 ;D  What a wonderful time we live in that the soot on a recovered S1 bugs us.

Offline Jcc

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Re: Refurbishment of Used Stages/Vehicles
« Reply #216 on: 04/16/2016 08:36 PM »
...
I tend to think it will not just be ten 3 second static firings; perhaps a series of firings at different lengths and thrust levels? Are there sufficient sensors on the stage to provide all the diagnostic information needed? Will they also borescope the engines? Laser scan the tanks to look for slight deformations?
...
Keep in mind that the Merlins have a finite total burn time and finite number of engine startups.

Doing borescoping and laser scans are time consuming. So doing such tasks for returned cores is unlikely IMO without some indication of problems from the telemetry.

In the long term, they should not have to do detailed inspections, but I think for the first several returned stages it is prudent to look carefully at the whole stage, including looking for any metal fatigue or cracking, or unexpected wear on any part. That's one of the benefits of getting the stage back, so you can look for any points of failure that don't show up in ground testing.

Musk said the things a stage should be good for 10-20 flights, then with "minor refurbishment" for up to 100. Refurbishment of what, and how do you know if it will last 10 flights or 20 flights? That knowledge will come with experience, and knowing what to check for.

Offline joek

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Re: Refurbishment of Used Stages/Vehicles
« Reply #217 on: 04/16/2016 09:58 PM »
The aviation industry already understands this very well, and is how the industry and the FAA establish norms and limits for airframe, engine, etc. inspections and tear-down/rebuild.  I doubt that the fact that this is a rocket will change the fundamental approach or process.

A. First steps:
1. Engine and air-frame wear characteristics?
2. Telemetry or other indications that tell you to inspect more closely?

B. Those drive second steps:
3. Event-driven inspection and level of inspection (e.g., went off-nominal, need to increase inspection frequency or more invasive inspection).
4. Event-driven tear-down and rebuild (e.g., went off-nominal, clear indication tear-down/rebuild required).
5. Time-driven inspection interval and level of inspection (e.g. more invasive inspection mandatory after X hours).
6. Time-driven tear-down/rebuild interval (e.g. tear-down/rebuild mandatory every Y hours).

SpaceX probably has a good model based on ground tests, but establishing norms and limits will require time.  Way too early to tell what those norms and limits will be.
« Last Edit: 04/16/2016 10:27 PM by joek »

Offline guckyfan

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Re: Refurbishment of Used Stages/Vehicles
« Reply #218 on: 04/16/2016 11:19 PM »
Keep in mind that the Merlins have a finite total burn time and finite number of engine startups.

Elon Musk has stated they have no meaningful limit. They just need exchange of some highly stressed parts.

Offline joek

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Re: Refurbishment of Used Stages/Vehicles
« Reply #219 on: 04/16/2016 11:39 PM »
Elon Musk has stated they have no meaningful limit. They just need exchange of some highly stressed parts.

Not to put too fine a point on it, but... the same could be said of almost any engine... rocket, aircraft or automotive.

The question is not: Will additional inspection-refurbishment-rebuild of various components be required; but: How often and at what cost?  IMHO, I hope and expect that SpaceX has done their homework, engineered appropriately, and that inspection-refurbishment-rebuild is cost effective.  And if not, I hope and expect they will make improvements to make them cost effective.

In any case, too early to tell.

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